It is important for a surgeon to identify characteristics of instruments which are being used in a surgical procedure in order to determine whether the instruments are appropriate for their intended use.
Certain characteristics of the instrument may be obvious from viewing while others may not. For example, in an endoscopic surgical cutting and stapling instrument, whether an appropriate stapling cartridge is in place in a stapling device, or whether staples have been fired, may not be readily apparent from viewing the instrument. Also in the use of instruments having interchangeable end pieces for use with a common handle because the parts are interchangeable, specific replaceable instrument characteristic may not be apparent from viewing the reusable instrument handle. As the cost of producing and sterilizing instruments are taken into consideration, more disposable, replaceable instrument parts are being used, particularly in endoscopic surgery. As a result, more frequently, surgeons are using instrument end pieces which may be interchangeably attached to a reusable handle portion or the like. Particularly in endoscopic surgery, these instruments may present some instrument characteristic identification difficulties because the surgeon cannot see the instrument in a direct manner but is watching on a video display and manipulating the instrument based on what is seen in the display.
Accordingly, the present invention provides a means for identifying surgical instrument characteristics. The identifying means may be used to identify certain predetermined characteristics of an end piece of a surgical instrument. For example, an end piece of an instrument may have a shaft with an end effector on its distal end. The end effector and shaft may form a replaceable end piece which may be coupled or uncoupled from a handle. Alternatively, a portion of the end piece such as the end effector itself or a portion of the end effector may be replaceable. For example, a stapling cartridge, may be removable and replaceable.
The end piece may have a variety of characteristics such as end effector type or configuration, instrument length or size, or instrument status. The identifying means for determining end piece or end effector characteristics designates the specific characteristics to the user or control unit, for example, of an electromechanical powered instrument. Preferably the identifying means is integral with the end piece and preferably is located in the end effector or the distal or operative end of the instrument.
A preferred embodiment incorporates the identification means in a linear cutting and stapling instrument. A linear cutting and stapling instrument has end effector jaws which engage tissue and apply parallel rows of staples to secure and join layers of tissue while a cutting means cuts between the rows of staples. A cartridge containing the staples is located in an end effector at the distal end of the stapling device. Various types of cartridges may be used with the same instrument, depending on the particular application of the instrument. For example, depending on the predetermined tissue type or thickness, different cartridges may be used to vary the size of the gap between the two jaws of the end effector used to engage tissue for stapling.
It is important to know whether the appropriate cartridge for the particular tissue or application is inserted in the end effector. For example, if a cartridge for thicker tissue is used in thin tissue, the desired hemostasis might not occur and uncontrolled bleeding may result when the tissue is cut. If a cartridge with a smaller gap is used in fragile tissue such as lung tissue, the tissue may be torn or unnecessarily damaged.
It is also important to know whether the staples have already been fired from the cartridge or not so that the user does not inadvertently cut tissue without a means for providing hemostasis.
Therefore it is desirable to provide an identifying means for indicating cartridge type and/or indicating whether the cartridge still contains staples or has been fired.
Color coding to distinguish cartridge type has been used. Also, a mechanical means for indicating cartridge status has been described. Mechanical lockout means have been described, for example, in U.S. Pat. Nos. 4,892,244 and 5,129,570. The mechanical lockout means mechanically prevent instrument refiring unless a single shot staple cartridge has been replaced and the instrument reset. However, an electrical means for determining cartridge type or status has not been disclosed.
Accordingly, one aspect of the present invention provides a means, preferably electrical, for determining a cartridge type of a stapling device.
Another aspect of the invention provides a means for determining cartridge status, i.e., whether staples are still present in the cartridge. Cartridge status may be determined by detecting whether or not the instrument has been fired or how many times the instrument has been fired.
If a one-shot staple cartridge is used, a detection means needs only to determine whether or not the device has been fired with the existing cartridge in place. If a multifire staple is used, the detection means counts the number of times the device is fired.
The means for detecting instrument firing is preferably electrical as described in the Detailed Description below. However, other means are contemplated by this invention. For example a magnetic sensor may be located on a stationary portion of the device. A driver for advancing a cutting blade or firing staples may have a magnetic element which advances past and is detected by the sensor when the device is fired. If, for example, a multiple fire cartridge is used, the sensor communicates the firing to a control unit. The control unit contains a logic circuit which counts the number of times a device is fired. Other means for sensing cartridge firing may include, e.g., optical means. The present invention also provides a means for preventing the use of the instrument when a cartridge has been spent, i.e., when no staples remain.
Preferably the present invention is incorporated into an instrument using electrical energy for other purposes, e.g., for cutting or cauterization or to provide electromechanical energy for instrument positioning and/or staple firing such as in an electromechanical cutter.
With increasing automation in surgery, it may be necessary for an instrument control unit in an automated device to be capable of recognizing certain predetermined instrument characteristics. An example of such a device is an electromechanical cutting and stapling device in which a control unit sequences the steps of electromechanically assisted instrument use. The control unit, or controller assists the stapling and cutting functions of the instrument by directing a suitable power means to operate the business head or end effector of the instrument to conduct a desired step in the procedure. The power source sends an electrical signal which is translated into electromechanical energy preferably either by or through a shaft. In preferred embodiments, the shaft is encased in a housing and a motion is provided to the shaft, i.e., rotation, longitudinal movement, etc. Means are disposed in the end effector to translate the motion of the shaft into a suitable force and/or motion in the head to carry out a desired step, i.e., to set and form staples or to sever tissue, etc. Examples of electromechanical cutters are described in U.S. Ser. Nos. 07/822,478, 07/991,619 and 08/91,807 incorporated herein by reference. An improved electromechanical cutter would recognize, e.g., whether the staple cartridge is appropriate for the tissue thickness and type of tissue it is intended to cut and staple.
Thus, one embodiment of the present invention, provides a means for determining instrument characteristics in an electromechanical cutter. A preferred embodiment provides an electromechanical device having a control unit for sequencing the steps of instrument use which also identifies the instrument characteristics. An electromechanical cutter is preferred in which the control unit uses means to identify the cartridge type and determine whether the staples have been fired. If the cartridge is inappropriate or the staples have been fired, then instrument use is locked out with a lock-out means. For example, the lock-out means may be contained in the logic of the control unit of an electromechanically powered stapling device. The control unit will not cause the device to fire if the electrical means indicates an inappropriate or fired instrument status. In one embodiment where a cutting device is used, the lock-out prevents advancing of the cutting blade with an inappropriate or spent cartridge.
An alternative means for determining instrument characteristics provides optical means for determining instrument characteristics. One embodiment provides light emitted from a control unit and reflected by the instrument. The light is sensed and converted into an electrical signal, e.g., using a photodiode associated with the control unit. The reflected light indicates a predetermined instrument characteristic for the particular reflected light signal. For example a different cartridge type would reflect light having a different intensity or wavelength.
Alternatively a discrete number of reflected light outputs either transmitting or blocking light, interface with a discrete number of light sensors which sense the transmitted light. The resulting light outputs have an on or off status (reflecting or blocking) thus representing a binary code preset to indicate specific end piece characteristics. An advantage of the optical means is the shaft portion including the light input surface, light pipe, and output lenses are capable of withstanding preferred radiation sterilization methods.